171 lines
5.5 KiB
C#
171 lines
5.5 KiB
C#
using OpenCvSharp;
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namespace SHH.CameraSdk;
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/// <summary>
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/// [消费者] 专用渲染线程（零延迟设计）
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/// 核心策略：
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/// <para>1. 容量为1的阻塞队列：仅保留最新一帧，杜绝帧堆积</para>
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/// <para>2. 非阻塞入队+主动丢帧：渲染慢时直接丢弃新帧，确保主线程不阻塞</para>
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/// <para>3. 引用计数联动：丢帧时立即释放引用，内存自动回池复用</para>
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/// </summary>
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public class FrameConsumer : IDisposable
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{
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#region --- 私有资源与状态 (Private Resources & States) ---
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/// <summary> 帧缓冲队列（容量1）：仅存储最新一帧，保证零延迟渲染 </summary>
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/// <remarks> BlockingCollection 封装线程安全操作，GetConsumingEnumerable 支持取消令牌 </remarks>
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private readonly BlockingCollection<SmartFrame> _frameBuffer = new(1);
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/// <summary> 取消令牌源：用于终止渲染循环 </summary>
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private readonly CancellationTokenSource _cts = new();
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/// <summary> 后台渲染任务 </summary>
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private Task? _renderTask;
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/// <summary> OpenCV 窗口名称 </summary>
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private readonly string _windowName;
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#endregion
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#region --- 构造与生命周期 (Constructor & Lifecycle) ---
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/// <summary>
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/// 初始化帧渲染消费者
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/// </summary>
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/// <param name="windowName">OpenCV 显示窗口名称</param>
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public FrameConsumer(string windowName = "Zero Latency Preview")
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{
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_windowName = windowName;
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}
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/// <summary>
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/// 启动渲染线程
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/// </summary>
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public void Start()
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{
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// 防止重复启动
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if (_renderTask != null) return;
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// 启动长期运行的渲染任务，提升线程调度优先级
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_renderTask = Task.Factory.StartNew(RenderLoop, TaskCreationOptions.LongRunning);
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Console.WriteLine($"[Consumer] 渲染线程启动成功，窗口名称: {_windowName}");
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}
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/// <summary>
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/// 停止渲染线程并清理资源
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/// </summary>
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public void Stop()
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{
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// 发送取消信号，终止渲染循环
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_cts.Cancel();
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// 标记队列完成添加，触发 GetConsumingEnumerable 退出遍历
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_frameBuffer.CompleteAdding();
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// 等待渲染任务结束（最多等待1秒，防止卡死）
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if (_renderTask != null)
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{
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Task.WaitAny(_renderTask, Task.Delay(1000));
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_renderTask = null;
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}
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// 清理队列残余帧：释放所有未消费帧的引用，防止内存泄漏
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while (_frameBuffer.TryTake(out var residualFrame))
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{
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residualFrame.Dispose();
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}
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Console.WriteLine($"[Consumer] 渲染线程已停止，窗口: {_windowName}");
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}
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#endregion
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#region --- 帧入队与渲染逻辑 (Frame Enqueue & Render Logic) ---
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/// <summary>
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/// [生产端入口] 接收帧并尝试入队（非阻塞）
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/// </summary>
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/// <param name="frame">待渲染的智能帧</param>
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public void Enqueue(SmartFrame frame)
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{
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// 防护：线程已停止，直接释放帧引用
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if (_cts.IsCancellationRequested)
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{
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frame.Dispose();
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return;
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}
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// 核心零延迟策略：非阻塞尝试入队
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// 队列满 → 上一帧未渲染完成 → 丢弃当前帧，释放引用
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if (!_frameBuffer.TryAdd(frame))
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{
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frame.Dispose();
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// Debug.WriteLine($"[Drop] 渲染线程[{_windowName}]处理过慢，丢弃一帧");
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}
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// 入队成功 → 帧由队列托管，等待渲染线程消费
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}
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/// <summary>
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/// 后台渲染循环（核心逻辑）
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/// </summary>
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private void RenderLoop()
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{
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// 创建 OpenCV 显示窗口
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Cv2.NamedWindow(_windowName, WindowFlags.Normal);
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try
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{
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// 阻塞遍历队列：队列空时等待，收到取消信号时退出
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foreach (var frame in _frameBuffer.GetConsumingEnumerable(_cts.Token))
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{
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try
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{
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// 渲染有效性校验：Mat 未释放且不为空
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if (frame.InternalMat != null && !frame.InternalMat.IsDisposed)
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{
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// 零拷贝渲染：直接引用 InternalMat，无内存复制开销
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Cv2.ImShow(_windowName, frame.InternalMat);
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// 1ms 等待 UI 事件响应（必须调用，否则窗口无响应）
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Cv2.WaitKey(1);
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}
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}
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catch (Exception ex)
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{
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Debug.WriteLine($"[RenderError] 窗口[{_windowName}]渲染失败: {ex.Message}");
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}
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finally
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{
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// 至关重要：渲染完成后释放帧引用
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// 引用计数归零 → 帧自动回池复用，避免内存泄漏
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frame.Dispose();
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}
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}
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}
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catch (OperationCanceledException)
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{
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// 正常取消，无需处理
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Debug.WriteLine($"[RenderInfo] 窗口[{_windowName}]渲染循环已取消");
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}
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finally
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{
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// 销毁 OpenCV 窗口，释放 UI 资源
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Cv2.DestroyWindow(_windowName);
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}
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}
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#endregion
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#region --- 资源释放 (Disposal) ---
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/// <summary>
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/// 释放所有资源
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/// </summary>
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public void Dispose()
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{
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Stop();
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_frameBuffer.Dispose();
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_cts.Dispose();
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}
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#endregion
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} |